This Annex Describes the various compatibility and address checks which should be carried out to ensure that best match of user and network capabilities is achieved on a call within an ISDN.
This Annex also covers interworking with existing networks.
Three different processes of checking shall be performed:
i) at the user-to-network interface on the calling side (see B.2);
ii) at the network-to-user interface on the called side (see B.3.2); and
iii) user-to-user (see B.3.3).
Note - In this context and throughout this Annex the term "called user" is the endpoint entity which is explicitly addressed.This may be an addressed interworking unit (IWU); see the I.500-Series Recommendations.
For details on the coding of the information required for compatibility checking see Annex I.